Charge forming apparatus



April 17, 1962 B. c. PHILLIPS CHARGE FORMING APPARATUS Sheets-Shae Filed Nov. 6 1958 INVENTOR 2 BERNARD E. PHILL 1P5.

ATTORNEY A ril 17, 1962 B. c. PHILLIPS 3,030,084

CHARGE FORMING APPARATUS Filed Nov. 6, 1958 2 Sheets-Sheet 2 INVENTOR BERNARD E1 PHILLIPS.

wugaamvw ATTORNEY United States Patent Q CHARGE FORMING APPARATUS Bernard C. Phillips, Toledo, Ohio, assignor to The Tillotson Manufacturing Company, Toledo, Ohio, a corporation of Ohio Filed Nov. 6, 1958, Ser. No. 772,357

10 Claims. (Cl. 261-41) This invention relates to charge forming devices or apparatus for use with internal combustion engines and more especially to apparatus for forming and delivering a fuel and air mixture to an internal combustion engine wherein the fuel constituent is delivered into the air solely by aspiration or differential pressure established through engine operation.

Internal combustion engines are being utilized extensively for powering lawn mowers, small boats, and the like and a charge forming device embodying a float-actuated fuel control valve is wholly unsuitable where the engines are required to be operated in angular positions. Charge forming devices embodying a diaphragm-controlled fuel supply means have been developed and used for such purposes but such devices heretofore employed require critical adjustment and satisfactory operation over a substantial rangeof engine speeds has been difficult.

The present invention embraces an arrangement for metering the fuel delivered to-=a mixing passage of a carburetor having a diaphragm-controlled fuel supply means whereby the delivery of fuelinto the mixing passage is calibrated to obtain a proportion of fuel to air in forming a charge which is satisfactory throughout substantially all engine speeds. 1

An object of the invention is the provision of a charge forming device embodying a diaphragm-controlled fuel supply means which is adaptable for use with two cycle or four cycle internal combustion engines.

Another object of the inventionresides in a charge forming device of the diaphragm-controlledtype embodying a fuel metering system wherein the resistance set up by capillary action in the fuel ducts and fuel metering means is substantially reduced or minimized to improve the delivery of fuel into a mixing passage during speed transition of the engine from idling or low speed operation to high speed operation.

Another object of the invention resides in a metering system for a charge forming device wherein the secondary fuel outlets for engine idling and low speed operations may be of substantial area rendering the adjustment of the system less critical and less sensitive whereby a proper fuel and air mixture is delivered under all conditions of operation of the engine.

Another object of the invention resides in a charge forming device or carburetor of the diaphragm type wherein one or more comparatively large secondary or low speed outlets are in communication with the main outlet or fuel discharge orifice whereby air bleeding through the main orifice into the idling system is obtained to render more reliable the operation of the engine at idling and low speeds.

Another object of the invention is the provision of a fuel delivery and metering system for a diaphragm type carburetor wherein the main fuel discharge nozzle or outlet opening into the mixing passage is arranged between the engine idling or secondary fuel discharge system and a constricted region in the fuel duct system whereby, during idling and low speed operation of the engine, the main fuel nozzle or outlet functions to admit air into the fuel delivered from the idling or secondary orifice system whereby the area of the fuel delivery orifice or orifices of the idling and low speed system are substantially greater with respect to the area of the main nozzle than sesame Patented Apr. 17, 1962 has been heretofore employed, rendering the operation of the carburetor more reliable in delivering the proper fuel and air mixture under various engine operating conditions.

Another object of the invention resides in a carburetor of the diaphragm type formed with a mixing passage incorporating a throttle means configurated to provide a substantial restricted zone in the mixing passage whereby the air stream moving through the mixing passage travels at comparatively high velocity at the region of discharge of fuel into the mixing passage.

Still another object of the invention is the provision of a charge forming device of the type utilizing an engineaspirated diaphragm for controlling delivery of fuel to an engine which is of simple, low cost construction embodying a minimum of passageways or fuel ducts providing more reliable idling operation of the engine and improved operation under governed control.

Further objects and advantages are within the scope of this invention such as relate to the arrangement, operation and function of the related elements of the structure, to various details of construction and to combinations of parts, elements per se, and to economies of manufacture and numerous other features as will be apparent from a consideration of the specification and drawing of a form of the invention, which may be preferred, in which:

FIGURE 1 is a top plan view illustrating one form of charge forming apparatus or carburetor of the invention, certain portions being shown in section for purposes of illustration; 7

FIGURE 2 is a longitudinal sectional view through the carburetor, the section being taken substantially on the line 2-2 of FIGURE 1;

FIGURE 3 is a bottom plan view of the carburetor shown in FIGURE 1 withzthe diaphragm removed and certain portions shown in section;

FIGURE 4 is a transverse; sectional view taken substantially on the line 4-4 of FIGURE 1;

FIGURE 5 is a top planview of a charge forming apparatus or carburetor showing a modified form of the invention; 4

FIGURE 6 is a longitudinal sectional view taken substantially on the line 6-6 of FIGURE 5;

FIGURE 7 is a bottom plan view of the structure shown'in FIGURE 5 with the diaphragm removed and a portion shown in section;

FIGURE 8 is a transverse sectional view taken substantially on the line 8-8 of FIGURE 5;

FIGURE 9 is a sectional view taken substantially on the line 9-9 of FIGURE 5, and

FIGURE 10 is a longitudinal sectional view similar to FIGURE 6 showing another form of the invention.

The apparatus of the present invention for delivering fuel and air mixture to an engine is adapted for use with either two or four cycle internal combustion engines and more especially the types of engine employed for powering lawn mowers, outboard marine engines and engines for various industrial purposes, but it is to be understood that the apparatus of the invention may be utilized with other engines or equipment and particularly engines that are to be operated in angular positions.

Referring to the drawings in detail, and initially to FIGURES 1 through 4, there is illustrated a charge forming apparatus or carburetor of the diaphragm type constructed to operate efiiciently with a minimum fuel lift distance whereby fuel may be readily delivered into a mixing passage and therein mixed with air providing combustible charges which may be delivered to either two cycle or four cycle internal combustion engines by reason of the aspirating effect of varying pressures effective in the mixing passage through engine operation.

The charge forming device or carburetor shown in FIGURES 1 through 4 includes a body or member formed with a mixing passage 12 which, in this form of construction, includes a Venturi 14, a main fuel outlet or orifice 16 opening into the Venturi for delivering fuel into the air stream admitted through an air inlet region 18 of the mixing passage.

A shaft 19 journalled in bearings provided by bosses 20 on the carburetor body is provided with a disk-type choke valve 21 disposed within the air inlet 18 for controlling the amount of air admitted to the mixing passage, an arm 22 being fixed to an extending portion of the shaft 19 for manipulating the choke valve 21.

One end of the carburetor body 10 is formed with a flange 23 adapted to be fitted to a boss portion 25 formed on a wall of a crankcase of an internal combustion engine, if of the two cycle type, or the flange 23 fitted to the manifold of an engine if the same is of the four cycle type. The flange 23 is secured in position by nuts 25' associated with stud bolts passing through openings formed in the flange.

The carburetor body is formed with a fuel chamber 24 which is disposed as close as possible to the mixing passage 12 in order to reduce to a minimum the lift or differential pressure required to flow fuel from the chamber 24 into the mixing passage. A Wall of the chamber 24 is formed by flexible impervious diaphragm or membrane 26 of generally circular shape, an annular gasket 27 being interposed between the carburetor body 10 and the diaphragm 26 as shown in FIGURE 2 to form a fluid tight seal. a

The diaphragm 26 is secured in place by means of a cover or closure plate 28 of circular shape. A plurality of screws 29 extend through aligned openings in the plate 28, the diaphragm 26 and gasket 27 into threaded openings in the carburetorbody 10 to hold these components in assembled relation as shown in FIGURES 2 and 4. The plate 28 is formed with a recessed circular region providing a space 30 to accommodate flexure or movement of the diaphragm, the plate being formed with a vent opening 32 to maintain atmospheric pressure in the space 30 between the plate and the diaphragm.

The gasket 27, diaphragm 26 and plate 28 are maintained in proper aligned condition by means of dowels or pilot pins 31 carried by the body 10 and projecting through suitable openings in the diaphragm, the gasket and the closure plate. A disk-type throttle valve 36 is disposed in the mixing passage 12 supported upon a shaft 38 journalled in bores formed in boss portions 39 and 40 formed on the body 10. An arm 42 is secured on one end of the throttle shaft for manipulating the throttle.

The shaft 38 is rotatable to vary the position of the throttle valve 36 for controlling the admission of fuel and air mixture to the engine to regulate the speed of the engine. The fuel chamber or passage 24 provides a reservoir for feeding fuel into the mixing passage 12. A main or primary fuel discharge outlet or orifice 16 delivers fuel into the choke band or region 15 of the Venturi 14 and, in addition, fuel is delivered through engine idling and low speed orifices 46 and 48 also referred to as secondary outlets or orifices. The method of supplying fuel to the outlets or orifices will be hereafter described.

FIGURES 2 and 4 particularly illustrate the diaphragm-controlled arrangement for regulating the flow of fuel from a supply into the fuel chamber 24 in accordance with the rate of fuel delivery into the mixing passage. The carburetor body 10 is formed with a boss portion 56 and a bore 51 having a threaded portion 52 to accommodate a connection (not shown) with a fuel supply such as gasoline or other hydrocarbon fuel. The carburetor body is formed with a second bore 54 having a threaded portion 55 in which is threaded a fitting or valve guide sleeve 56.

Slidably mounted in the hollow interior of the sleeve 56 is a valve member 58 of polygonally shaped crosssection, the valve member being loosely mounted in the sleeve or fitting 56. The member 58 is formed at its upper extremity with a cone-shaped or needle valve portion 60 which cooperates with an annular valve seat 62 disposed in the upper end of the fitting 56. The annular valve seat 62 is preferably formed of resilient rubber-like material, such as Buna (butadiene-styrene copolymer), neoprene (chloroprene) or other material which is resistant to deterioration by hydrocarbon fuels.

The opening or passage in the valve seat 62 is of comparatively small diameter so that the effective fuel pressure acting against the cone-shaped valve portion 60 is reduced to a minimum in order to provide for sensitive operation of the fuel control mechanism. The passage in the seat 62 is in communicationwith the fuel inlet bore 51 by means of a connecting duct or passage 64. The region of the body 10 defining a wall of the chamber 24 is formed with an elongated recess 66 forming a part of the chamber 24 and accommodates a lever or lever member 68 which is pivotally supported or fulcrumed upon a pin 70.

The diaphragm 26 is provided at its opposite sides with reinforcing disks 72 and 73 formed of metal or other suitable material and are held together and to the diaphragm by means of a headed member 75. The head of member 75 is in contact with one arm 77 of the lever 68, while the other arm 79 of the lever member is in contact with the lower end of the valve member 58. A coil spring 80 is contained in a suitable bore adjacent the recess 66 and is disposed between the bottom of the bore and the lever arm 77 for yieldably biasing the lever 68 in a clockwise direction as viewed in FIGURE 4 to'urge the valve portion 60 of valve member 58 into closed position in contact with the valve seat 62 to interrupt fuel flow into the chamber 24.

As fuel is delivered from the chamber 24 into the mixing passage 12 under the influence of engine aspiration, the pressure in chamber 24 is reduced, the diaphragm 26 is flexed upwardly. This action moves the lever 68 to release pressure on the valve member 58 permitting fuel to flow through the passage in the valve seat 62 along the facets of the polygonally shaped valve member 58 into the chamber 24. It should be noted that the chamber 24 is not vented to the atmosphere so that reduced pressure is set up in this chamber by reduced pressure in the mixing passage caused by aspiration of the engine.

There is no defined or predetermined level of fuel in the chamber 24. The flow of fuel into the chamber 24 slightly increases the pressure in the chamber 24 and, under the influence of the expansive coil spring 80, the lever member 68 is swung in a clockwise direction about its pivot 70, as viewed in FIGURE 4, elevating the valve member 58 and closing the passage in the seat 62 to interrupt the flow of liquid fuel into the chamber 24 until discharge of fuel into the mixing passage 12 again reduces the pressure in the fuel chamber 24.

During engine operation, it is found that a pressure balance is substantially maintained and the valve portion 60 is constantly open to admit fuel flow into the chamber 24 equal to the rate of delivery of fuel into the mixing passage 12.

The charge forming device or carburetor of the present invention is inclusive of a fuel metering system which is herein referred to as a uniflow metering system. The principle involved in this system is the delivery of fuel from the chamber 24 to a region from which fuel is dis-- charged from the main orifice or outlet 16 and from the secondary or idling and low speed orifices or outlets. All of the fuel delivered through the main and secondary orifices is metered by a master or primary metering means Whether it is discharged through the primary orifice 16 or through the secondary orifices 46 and 48. This arrange-- inent facilitates bleeding air at idling and low engine speeds into the fuel supplied to the secondary idling or low engine speeds into the fuel supplied to the secondary idling or low speed orifices.

Formed in the carburetor body 16 and at the lower terminus of the main discharge outlet 16, is a duct or region '82 slightly larger than the bore of the discharge orifice 16, the region 82 being isolated from chamber 24 by means of a plug or disk 84 shown in FIGURE 2. The body of the carburetor adjacent the recess 66 is formed with a fuel channel or duct 86 which is in communication with the region or fuel distribution duct 82 by a metering passage 9%.

The body of the carburetor is provided with a bore adapted to accommodate a metering means in the form of a member 92 which has a tapered mcteringneedle portion 94 extending into the metering passage 90. The member 92 is threaded into a threaded portion of a bore 93 in the body it) and is formed with a knurled knob 96.

' By manipulating the knob 96, the member 92 may be rotated'in the threaded bore to adjust the position of the metering needle 94 in the metering passage 90 to regulate or meter the flow of fuel from the chamber 24 through passages 86 and 90 into the region 82 immediately beneath the main fuel discharge orifice 16.

The channel or duct 93 containing the metering needle construction 92 is connected by means of a duct 97 with a duct or channel 98. Disposed in the channel 98 is a second metering means for regulating or controlling the delivery of fuel to the secondary orifices 46 and 48. The metering means in the channel 98 comprises a member 1% provided with a threaded portion engaging in a threaded portion of the channel wall for adjusting the member 100 lengthwise of the channel 98.

As shown in FIGURE 2, there is formed in the body 10 adjacent the secondary orifices 46 and 48, a recess or supplemental chamber 102, the lower wall of the chamber 192 being a plug or cap member 165, the chem her 102 accommodating delivery of liquid fuel through the secondary orifices 46 and 48. The chamber 102 is in communication with the channel 98 by means of a restricted passage 1%. The valve member 1&0 is formed with a tenon portion of reduced diameter which terminates in a cone-shape or needle valve portion 106 arranged to project into the restricted passage 104.

The valve member 106 is provided with a knurled portion 168 to facilitate adjustment of the valve member 160 to regulate the flow of fuel through the restricted passage 164. The body It is formed with recesses lit) and 112 adjacent the respective valve members 92 and 160 to ac commodate expansive coil springs 114 and 116 which provide a frictional component to retain the valve members in their adjusted positions.

As particularly shown in FIGURES l and 2, a passage 118 of comparatively small cross-sectional area may be employed to establish communication between the air inlet end 18 of the mixing passage 12 and the region 82 adjacent the main discharge orifice 1-6. The passage 118 forms an air bleed for admitting air from the inlet end 18 of the mixing passage for admixing with the fuel in the region 82 providing an emulsion of fuel and air discharged from the main and supplemental or secondary orifices into the mixing passage.

The operation of the charge forming device or car buretor illustrated in FIGURES 1 through 4 is as follows: The carburetor may be connected with an engine of either the two cycle type or the four cycle type, both types providing aspiration by reason of reduced pressure for influencing fiow of fuel and air mixture through the mixing passage 12 into the engine crankcase or manifold connected with the flange 23 of the carburetor body. During the starting operations of the engine with which the carburetor is used, the choke valve 21 is moved to substantially closed position and the throttle valve 36 to an open or partially open position, the aspiration set up by 5 reciprocation of the engine piston or pistons effecting discharge of fuel from one or more of the orifices 16, 46 and 48.

As soon as the engine is started, the choke valve 21 is moved to open position as shown in FIGURE 2 and, if an idling operation of the engine is desired, the throttle valve 36 is substantially closed as indicated by the broken line position at 37 in FIGURE 2.

In this position of the throttle valve, fuel flow takes place from the diaphragm chamber 24 through the passages or ducts 86 and 90 and pats the primary metering needle or valve 94 through the passages 96 and 98 and past the second metering valve 106 through the passage 104 into the auxiliary or supplemental chamber 102, and the fuel discharged through the engine idling orifice 46.

In idling operation of the engine, comparatively high aspiration or suction is eifective to discharge fuel through the orifice 46. During this period, the pressure in the Venturi region of the mixing passage is near atmospheric pressure end, due to the high suction upon the orifice 46, air flows from the Venturi region in a reverse direction through the primary orifice 16 and is mixed with the fuel in the region 82 so that an emulsion of fuel and air is delivered through the idling orifice 46.

As the throttle valve 36 is moved toward partial open position as indicated in broken lines at 39, the engine aspiration initiates the discharge of fuel and air emulsion through the low speed orifice 48, supplementing the fuel and air discharged from the engine idling orifice 46 thereby supplying an increased flow of combustible mixture to the engine. During fuel discharge from the orifices 46 and 48, the pressure in the Venturi 14 is only slightly reduced so that air continues to fiow through the orifice 16 into the region 82 to provide the fuel and air bled mixture for the orifices 46 and 48.

As the throttle '36 is moved toward open position, the air flow through the Venturi is increased and the pressure at the choke band 15 of the Venturi reduced whereby fuel from the region 82 is then discharged through the primary or main orifice 16 into the Venturi. As the engine speed increases, the discharge of fuel and air mixture from the engine idling and low speed orifices 46 and 48 is substantially reduced, and, at high engine speeds, discharge of fuel and air mixture through these orifices may cease entirely. Theair admitted through the passage 118 into the region 82 beneath the main orifice 16 bleeds into the fuel discharged from the main orifice and the idling and low speed orifices. During fuel discharge from the main orifice 16, there is substantially no back bleeding of air into region 8-2 from the engine idling and low speed orifices 46 and 43. One of the features of the arrangement shown in FIGURES 1 through 4 is that the main nozzle or discharge outlet 16 and region 82 are arranged between the metering restriction provided by the valve 94 and the engine idle and low speed fuel delivery system. While a comparatively weak capillary seal is formed by the liquid fuel in the main nozzle outlet passage, such capillary seal is readily broken or disrupted by the engine aspiration effective on the idle and low speed orifices so that there is sutficient air bleeding from the mixing passage through the main orifice into the fuel supplied to the secondary orifices 46 and 48'. Thus the main nozzle or outlet 16 is caused to act as an air bleed for the fuel supplied to the mixing passage through the orifices 46 and 48 during idling and low speed operation of the engine. Under idling or low speed conditions, air bleeds into the fuel concurrently through the ports or passages 16 and 118.

Under high speed engine operation, the fuel admitted from the diaphragm chamber 24 past the needle valve 94 flows directly from region 82 through the main orifice 16 into the Venturi, the amount of fuel admitted to the region 82 being determined by the adjustment of the primary or high speed adjusting needle 94. As the engine speed increases, the discharge of fuel and air mixture through the orifices 46 and 48 is reduced while the discharge of air bled fuel through the main nozzle 16 is increased.

The calibration of the ratio of fuel to air in the air bled mixture discharged from the main orifice 16 is dependent in a large measure upon the cross-sectional area of the air bleed passage 118. If a leaner mixture is desired at high engine speeds, the cross-sectional area of the passage 118 is made larger. It should be noted that the air bleed passage 118 has only a minor effect on the amount of air bled into the idling and low speed system as it merely augments the greater amount of air admitted through the main discharge orifice into the low speed and engine idling arrangement.

This factor does not adversely affect the idle and low speed arrangement as the ports or orifices 46 and 48 may be increased in size to compensate for the additional air bled through passage 118 into the system. The air bleed passage 120 performs an additional function in that it speeds up the delivery or discharge of fuel into the Venturi through the main orifice 16 when the throttle 36 is suddenly opened.

As fuel is withdrawn from the diaphragm chamber 24 and delivered through one or more of the outlets or orifices into the mixing passage under the influence of engine aspiration, the diaphragm 26 is moved upwardly, as viewed in FIGURES 2 and 4, by reason of the reduced pressure set up by engine aspiration, causing the member 75 to tilt the lever 68 counterclockwise about its fulcrum 70 as viewed in FIGURE 4, permitting the valve member 58 to move downward whereby the needle portion 16 moves away from the seat member 62 to admit fuel from a supply into the chamber 24 to replace the fuel discharged into the mixing passage.

Fuel flow to the carburetor may be supplied from a tank or container by gravity or may be supplied by a fuel pump. It should be pointed out that the passage 96 is of comparatively large size whereby aspiration or reduced pressure in the channel or passage 96 is effective not only to bleed air through the main nozzle 16 into the idling and low speed system but to break or fracture any potential capillary fuel seal occurring at the region of the metering needle 94. This is advantageous in that it permits the use of larger low speed and idling orifices 46 and 48.

Through the use of large supplemental orifices and fuel conveying passages, the functioning and operation of the carburetor is rendered less sensitive and there is less liability for the passages and orifices to become clogged so that more reliable operation of the carburetor is assured.

In a carburetor of this character embodying a diaphragm control inlet valve and the diaphragm normally disposed in horizontal position, there is no head of fuel on the main orifice and, since sufficient aspiration must be applied through the orifice to the diaphragm chamber 24 in order to operate the diaphragm and overcome the pressure of the spiring on the lever 68, the passages or ducts conveying fuel to the supplemental fuel discharge orifices 46 and 48 must necessarily be comparatively large in relationship to the size of the primary or main discharge orifice 16.

It will be apparent that the arrangement shown in FIGURES 1 through 4 provides for the metering of all of the fuel discharged into the mixing passage by the main metering means or needle 94 so as to facilitate the bleeding of air into the fuel delivered into the mixing passage through the secondary orifices 46 and 48. The amount of fuel and air mixture delivered into the supplemental chamber 102 for discharge through the secondary orifices may be individually regulated by manipulation of the metering needle valve 106.

FIGURES 5 through 9 illustrate a modified form of the invention wherein the main fuel discharge and engine idling or secondary fuel discharge arrangements are, in effect, combined and a single adjustment employed for metering or regulating fuel flow to the main and secondary discharge system. In this form, the carburetor body is formed with a flange 23 for securing the carburetor to an engine crankcase or an engine manifold. The body 120 is formed with a mixing passage 122 having an air inlet portion 124 and a restricted portion 126 of slightly smaller diameter than the air inlet portion 124.

A choke valve 21' is mounted upon a rotatable shaft 19' for restricting the air supply to the mixing passage during engine starting operations. Disposed in the restricted band 126 of the mixing passage is a throttle 36 mounted upon a rotatable shaft 38 for controlling or regulating the flow of fuel and air mixture to the engine.

The body 120 is formed with a fuel chamber 24, one wall of which is defined by a diaphragm 26 formed of flexible material, a gasket 27 being disposed between the periphery of the diaphragm and the body 120. A plate 28 secures the diaphragm 26' and gasket 27' in the position shown in FIGURE 6, these components being retained in assembled relation by screws 29'.

The diaphragm-controlled arrangement for regulating the ingress of fuel into the fuel chamber 24 is substantially the same as shown in the form of the invention illustrated in FIGURES 1 through 4. The central region of the diaphragm 26 is provided with a headed member 75' which engages one arm of a lever 68' the latter being fulcrumed upon a pin as at 70'. A fitting 55 extends into a bore formed in the body 129 and slidably accommodates a valve member 58' having a cone-shaped valve portion 60' cooperating with a valve seat 62 as illustrated in FIGURE 8.

A fuel supply tube (not shown) is connected with a threaded portion 52' of an inlet passage in communication with the annular opening or duct in the valve seat member 62 for conveying fuel from a supply (not shown) into the fuel chamber 24.

In the operation of the carburetor, the reduced pressure impressed in the fuel chamber 24 by engine aspiration transmitted through the fuel discharge system is effective to elevate or flex the diaphragm, swinging the lever 68 in a counterclockwise direction as viewed in FIGURE 8, compressing the spring 80' and thus releasing pressure upon the valve member 58 whereby the latter moves downwardly, withdrawing the valve portion 60 from the seat 62' to facilitate fuel flow into the fuel chamber 24.

The arrangement shown in FIGURES 5 through 9 includes a fuel duct system for delivering or conveying fuel from the fuel chamber 24' into a supplemental chamber or region 130 adjacent the main orifice 132 and the supplemental orifice 134. The supplemental chamber 130 is separated from chamber 24 by means of a disk or Welsh plug 136. Formed in the carburetor body 120 is a bore adapted to accommodate an adjustable fuel regulating or metering means. As particularly illustrated in FIGURE 5, the metering means includes a valve member 138 having a threaded portion 139 which engages a threaded region in the bore accommodating the valve member.

The valve member is provided with a manipulating knob or finger grip 140 for adjusting the valve, an expansive coil spring 142 serving to frictionally retain the valve member 138 in adjusted position. The member 138 is formed with a metering needle or tapered valve portion 144 which extends into a bore 146. A restricted duct 148 establishes communication of the supplemental chamber 130 with the duct 146 as shown in FIGURE 5. The cone-shaped or tapered extremity of the valve portion 144 cooperates with the entrance of the restriction 148 to regulate or meter the fuel flow to the supplemental chamber 130.

A duct 150 establishes communication between the fuel chamber 24' and the duct 146. Thus, fuel from chamber 24' flows through the ducts 150, 146 and 148 into the supplemental chamber or region 130 and the fuel discharged therefrom through the main and supplemental orifices into the mixing passage 122. An air bleed passage 152 is arranged between the air inlet end of the mixing passage and the supplemental chamber 130 to facilitate bleeding air into the fuel in the supplemental chamber 130 so that an emulsion or mixture of fuel and air is delivered from the main and supplemental orifices during engine operation.

It should be noted that in the arrangementillustrated in FIGURES through 9, a single control member 144 meters or regulates the flow of fuel for discharge through the main and supplemental orifices from the fuel reservoir or supplemental chamber 130 into the mixing passage.

The operation of the arrangement shown in FIGURES 5 through 9 is as follows: To initiate engine operation, the choke valve 21 is moved to closed position as shown in broken lines in FIGURE 6, the throttle valve 36"being preferably in partial or full open position. When the throttle 36' is moved to substantially closed or idle position, as illustrated in broken lines in FIGURE 6, the main orifice or fuel outlet port is at the left side of the valve 36 as viewed in FIGURE 6. i

In this position of the throttle valve, the engine aspiration is effective on the supplemental or engine idling and low speed orifice 134 to cause air to flow from the air inlet side 124- of the mixing passage through the air bleed passage 152 and the main fuel discharge port 132 into the supplemental chamber 130 and is mixed with the fuel so that an emulsion of fuel and air is delivered through the engine idling or low speed orifice 134.

This action ensues by reason of the engine aspiration setting up a reduced pressure at the right side of the throttle valve 36 in closed position to cause a reverse flow of air from the mixing passage through the main orifice 132 into the chamber 130. As the throttle 36 is moved toward open position, a progressively increased velocity of air through the mixing passage is established'under the influence of increased aspiration by the engine so that fuel and air discharge through the supplemental orifice 134 is gradually decreased and the air bleeding through the main nozzle 132 ceases, and delivery of fuel from chamher 130 into the mixing passage through the main orifice 132 takes place.

There may be a period in the opening of the throttle wherein fuel and air mixture may be concomitantly delivered from both main and supplemental orifices 132 and 134, but as the engine speed increases and aspiration is increased, fuel discharge from the supplemental orifice 134- decreases, and at open or nearly open position of the throttle, substantially all of the fuel delivered into the mixing passage is through the main orifice 132. An emulsion is at all times delivered through the main orifice 132 when the air bleed passage 152 is provided. The air bleed 152 maybe omitted when the carburetor is employed in certain installations! It should be noted that all of the fuel delivered into the mixing passage, either by Way of the main outlet or orifice 132 and the supplemental orifice 134, is metered or regulated by the relative position of the single metering valve 144. As fuel is withdrawn from the diaphragm chamber 24', the diaphragm is elevated under the influence of reduced pressure eifective in the chamber 24 which actuates the lever 68 and the valve member 58' to admit fuel into the chamber 24 from the supply in an amount commensurate or equal to the rate of delivery of fuel into the mixing passage 122.

FIGURE is a view similar to FIGURE 6 illustrating a modified form of throttle valve construction and air bleed arrangement. In this form the carburetor body 120", the fuel chamber 24", the diaphragm 26", the clo sure member 28 and the fuel inlet flow control means are substantially the same as the corresponding components shown in the arrangement of FIGURES 5 through 9. A supplemental fuel chamber 13%" receives. fuel from the fuel chamber 24" by a duct system of the same character as illustrated in FIGURES 5 through 9.

A main or primary orifice 160 and a secondary or engine idling orifice 162 are arranged to deliver fuel into the mixing passage 122" from the supplemental chamber A choke valve 21" is provided of the same character as illustrated in FIGURES 5 and 6. The throttle valve construction in this form of the invention is shaped or configurated to provide a supplemental restriction in the mixing passage 122" to effect a substantial increase in the velocity of air moving through the mixing passage adjacent the main orifice when the throttle valve is in partially open or full open position.

The shaft 164 supporting the throttle valve arrangement is provided with a flattened portion in the mixing passage 122" adapted to support a throttle member formed with a relatively thin, generally semicircular disk 166 extending toward the outlet end of the mixing passage 122" and a second valve portion 168 of substantial thickness as shown in FIGURE 10. The thin semicircular disk portion 166 extends through a slot provided in the shaft 64 and the valve construction secured to the throttle shaft 164 by means of a securing screw 170.

The thickened valve portion 168, when in partial or full open throttle position, presents a substantial restriction to the passage or flow of air through the mixing passage adjacent the main orifice 160 so as to increase the air velocity through the mixing passage at this region. Thus this arrangement functions in a manner similar to that of a Venturi construction. The air bleed arrangement for supplying air to the supplemental chamber 130 to be mixed with the fuel delivered into the mixing passage is in the form of a tubular member 174 which extends into the mixing passage a substantial distance from the wall thereof and is adapted to conduit air from the air inlet end of the mixing passage into the supplemental chamber 130".

It should be noted that the entrance to the tubular air bleed member 174 is arranged in the path of high velocity air flow when the throttle valve construction is in partial or full open position so as to foster the flow of air through the air bleed tube 174 into the supplemental fuel chamber 130".

The operation of this form of construction is similar to the arrangement illustrated in FIGURE 6 except that a higher velocity air flow for a given engine speed is obtained through the mixing passage at the region of the main fuel discharge orifice by reason of the restriction provided by the enlarged valve portion 168. The flow of air into the supplemental fuel reservoir 130 for air bleed purposes is increased by reason of the positioning of the entrance of the tube 174 in the direct path of the high velocity air flow through the mixing passage. It is apparent that, within the scope of the invention, modifications and dilferent arrangements may be made other than is herein disclosed, and the present disclosure is illustrative merely, the invention comprehending all variations thereof.

I claim:

1. In combination, a charge forming device for an in ternal combustion engine including a body formed with a mixing passage, a fuel receiving chamber formed in the body, a flexible diaphragm forming a wall of the chamber, a main fuel outlet for delivering fuel from the chamber into the mixing passage, a supplemental fuel outlet for delivering fuel from the chamber into the mixing passage, said main and supplemental fuel outlets opening into the mixing passage at one side of a plane through the axis of the mixing passage, a fuel inlet passage formed in the body arranged to convey fuel from a supply into the fuel receiving chamber, a valve in said inlet passage, means including a lever for transmitting movements of said diaphragm to said valve for regulating fuel flow into the fuel chamber, means including a duct formed in said body for conveying fuel from the fuel chamber to the main and supplemental fuel discharge outlets, an air passage opening intq the mixing passage arranged to bleed air into the fuel prior to'its discharge through the main and supplemental outlets, and means for metering the fuel flow from the chamber to the main and supplemental outlets.

2. In combination, a charge forming device for an internal combustion engine including a body formed with a mixing passage, a fuel receiving chamber formed in the body, a flexible diaphragm forming a wall of the chamber, a main fuel outlet for delivering fuel from the chamber into the mixing passage, a supplemental fuel outlet for delivering fuel from the chamber into the mixing passage, a fuel inlet passage formed in the body arranged toconvey fuel from a supply into the fuel receiving chamber, a valve in said inlet passage, means including a lever for transmitting movements of said diaphragm to said valve for regulating fuel flow into the fuel chamber, means including a duct formed in said body for conveying fuel from the fuel chamber to the main and supplemental fuel discharge outlets, adjustable valve means in said duct for metering the fuel flow from the chamber to the main and supplemental outlets, and an air bleed passage arranged to admit air into the fuel prior to its discharge through the main outlet and the supplemental outlet into the mixing passage.

3. In combination, a charge forming device for an internal combustion engine including a body formed with a mixing passage, a relatively shallow fuel receiving chamber formed in the body, a flexible diaphragm responsive to varying the pressure in the mixing passage forming a wall of the chamber, a main fuel outlet for delivering fuel from the chamber into the mixing passage, a supplemental fuel outlet for delivering fuel from the chamber into the mixing passage, a fuel inlet passage formed in the body arranged to convey fuel from a supply into the fuel receiving chamber, a valve in said inlet passage, means including a lever for transmitting movements of said diaphragm to said valve for regulating fuel flow into the fuel chamber, a duct formed in said body for conveying fuel from the fuel chamber to the region of the main and supplemental fuel discharge outlets, manually adjustable valve means in said duct for metering the fuel flow from the chamber to the main and supplemental outlets, and an air bleed passage between the mixing passage and the region of the main outlet for admitting air into the fuel prior to its discharge through the main outlet and supplemental outlet into the mixing passage.

4. In combination, a charge forming device for an internal combustion engine including a body formed with a mixing passage, a relatively shallow fuel receiving chamber formed in the body, a flexible diaphragm responsive to varying pressure in the mixing passage forming a wall of the chamber, a main fuel outlet for deliven'ng fuel from the chamber into the mixing passage, a supplemental fuel outlet for delivering fuel from the chamber into the mixing passage, said main and supplemental fuel outlets being arranged in a wall region of the mixing passage nearest the diaphragm, a fuel inlet passage formed in the body arranged to convey fuel from a supply into the fuel receiving chamber, a valve in said inlet passage, means including a lever for transmitting movements of said diaphragm to said valve for regulating fuel flow into the fuel chamber, a plurality of interconnected ducts formed in said body arranged to convey fuel from the chamber to the main and supplemental outlets, an air bleed passage opening into the mixing passage arranged to bleed air into the fuel prior to its discharge through the main and supplemental outlets, and manually adjustable fuel metering valve projecting into one of said ducts and adapted to regulate the fuel flow to both said main and supplemental orifices.

5. In combination, a charge forming device for an internal combustion engine including a body formed with a mixing passage, a fuel receiving chamber formed in the body, a flexible diaphragm responsive to varying pressure in the mixing passage forming a wall of the chamber,

a main fuel outlet for delivering fuel into the mixing passage, a supplemental fuel outlet for delivering fuel into the mixing passage, a fuel inlet passage formed in the body arranged to convey fuel from a supply into the fuel receiving chamber, a valve in said inlet passage, means including a lever for transmitting movements of said diaphragm to said valve for regulating fuel flow into the fuel chamber, a plurality of interconnected ducts formed in said body arranged to convey fuel from the chamber to the main and supplemental outlets, a manually adjustable fuel metering valve projecting into one of said ducts and adapted to regulate the fuel flow to both said main and supplemental orifices, and an air bleed passage between the mixing passage and the main orifice for admitting air to the fuel discharged from the main outlet and supplemental outlet into the mixing passage.

6. In combination, a charge forming device for an internal combustion engine including a body formed with a mixing passage, a relatively shallow fuel receiving chamber formed in the body, a flexible diaphragm responsive to pressure variations in the mixing passage forming a wall of the chamber, a main fuel outlet for delivering fuel into the mixing passage, a supplemental fuel outlet for delivering fuel into the mixing passage, a fuel inlet passage formed in the body arranged to convey fuel from a supply into the fuel receiving chamber, a valve in said inlet passage, means for transmitting movements of said diaphragm to said valve for regulating fuel flow into the fuel chamber, a plurality of interconnected ducts formed in said body arranged to convey fuel from the chamber to the main and supplemental outlets, a manually adjustable fuel metering valve projecting into one of said ducts and adapted to regulate the fuel flow to both said main and supplemental outlets, a throttle valve in said mixing passage, said throttle valve having a semicircular portion of substantial thickness forming a restriction in the mixing passage.

7. In combination, a charge forming device for an internal combustion engine including a body formed with a mixing passage, a relatively shallow fuel receiving chamber formed in the body, a flexible diaphragm responsive to pressure variations in the mixing passage forming a wall of the chamber, a main fuel outlet for delivering fuel into the mixing passage, a supplemental fuel outlet for delivering fuel into the mixing passage, a fuel inlet passage formed in the body arranged to convey fuel from a supply into the fuel receiving chamber, a valve in said inlet passage, means including a lever for transmitting movements of said diaphragm to said valve for regulating fuel flow into the fuel chamber, a plurality of interconnected ducts formed in said body arranged to convey fuel from the chamber to the main and supplemental outlets, a manually adjustable fuel metering valve projecting into one of said ducts and adapted to regulate the fuel flow to both said main and supplemental outlets, an air bleed passage between the mixing passage and the main orifice for admitting air to the fuel discharged from the main outlet and the supplemental outlet into the mixing passage, a throttle valve in said mixing passage, said valve having a semicircular portion of substantial thickness forming a restriction in the mixing passage.

8. In combination, a charge forming means for an internal combustion engine including a body formed with a mixing passage, a relatively shallow fuel receiving chamber formed in the body in close proximity to the mixing passage, a flexible diaphragm responsive to pressure variations in said mixing passage forming a wall of said chamber, a main fuel outlet for delivering fuel into the mixing passage, a supplemental fuel outlet for delivering fuel into the mixing passage, a fuel inlet passage formed in said body, a valve in said inlet passage, means including a lever responsive to movements of the diaphragm for controlling said fuel inlet valve, a duct arrangement formed in said body for conveying fuel from said chamber to the main and supplemental outlets, a first means for metering fuel delivered to both main and supplemental outlets, a second means for regulating fuel delivered to the supplemental outlet, and an air bleed passage for admitting air to the fuel delivered to the'main and supplemental outlets.

9. In combination, a charge forming means for an internal combustion engine including a body formed with a mixing passage, a fuel receiving chamber formed in the body, a flexible diaphragm responsive to pressure varia tions in the mixing passage forming a wall of said chamber, a main fuel outlet for delivering fuel into the mixing passage, a supplemental fuel outlet for delivering fuel into the mixing passage, said main and supplemental fuel outlets being arranged in a wall region of the mixing passage at one side of a plane through the axis of the mixing passage, a fuel inlet passage formed in said body, a valve in said inlet passage, means including a lever responsive to movements of the diaphragm for controlling said fuel inlet valve, a duct arrangement formed in said body for conveying fuel from said chamber to the main and supplemental outlets, an air passage in communication with the mixing passage for admitting air into the fuel prior to its delivery through the main and supplemental outlets, a first manually adjustable valve means for metering fuel delivered to both main and supplemental outlets, and a second manually adjustable means for regulating fuel delivered to the supplemental outlet.

10. in combination, a charge forming means for an internal combustion engine including a body formed with a mixing passage, a relatively shallow fuel receiving chamber formed in the body in close proximity to the mixing passage, a flexible diaphragm responsive to pressure variations in the mixing passage forming a wall of said chamber, a main fuel outlet for delivering fuel into the mixing passage, a supplemental fuel outlet for delivering fuel into the mixing passage, said main and supplemental fuel outlets being arranged in a Wall region of the mixing passage at one side of a plane through the axis of the mixing passage, a fuel inlet passage formed in said body, a valve in said inlet passage, means including a lever responsive to movements of the diaphragm for controlling said fuel inlet valve, a duct arrangement formed in said body for conveying fuel from said chamher to the main and supplemental outlets, a first manually adjustable valve means for metering fuel delivered to both main and supplemental outlets, a second manually adjustable means for regulating fuel delivered to the supplemental outlet, and an air bleed passage opening into the mixing passage for admitting air to the fuel delivered through the main outlet and supplemental outlet to the mixing passage.

References Cited in the tile of this patent UNITED STATES PATENTS 2,199,509 Olson May 7, 1940 2,733,902 Phillips Feb. 7, 1956 2,774,582 Bracke Dec. 18, 1956 

